Field of the Invention
The present invention relates to a light source apparatus and an image display apparatus.
Description of the Related Art
Conventionally, a light source apparatus that includes a B-LED and a conversion member having an R phosphor and a G phosphor has been proposed as a backlight apparatus for liquid-crystal display apparatuses. The B-LED is a light-emitting diode (LED) that emits blue light. The R phosphor is a phosphor that emits red light by being excited with blue light. The G phosphor is a phosphor that emits green light by being excited with blue light. In such a light source apparatus, when blue light is emitted from the B-LED, red light is emitted from the R phosphor and green light is emitted from the G phosphor. The blue light from the B-LED, the red light from the R phosphor, and the green light from the G phosphor are combined to form combined light which is emitted from the light source apparatus. The use of such a light source apparatus enables light having a wide color gamut to be obtained as light emitted from the light source apparatus.
Such a light source apparatus has a problem in that, since the excited light (the blue light emitted from the B-LED) enters at various incidence angles in relation to the conversion member, a brightness unevenness or a color unevenness occurs in the light emitted from the light source apparatus. Japanese Patent Application Publication No. 2009-140829, for example, disclosed a technique for solving this problem. The technique disclosed in Japanese Patent Application Publication No. 2009-140829 uses a light beam control element that bends the light from an LED in a direction vertical to a light-emitting surface of a conversion member (phosphor layer).
Moreover, in recent years, quantum dots have been proposed as phosphors (wavelength conversion elements) capable of generating highly pure light by being excited. A quantum dot is a phosphor that emits light of color corresponding to the size of the quantum dot by reacting to ultraviolet light or blue light. Since the use of quantum dots enables red light or green light having a half-value width of approximately 40 nm to be obtained from blue light, it is possible to obtain light having a higher color gamut as the light emitted from the light source apparatus. Japanese Patent Application Publication No. 2012-022028, for example, discloses a light source apparatus which uses quantum dots. In the technique disclosed in Japanese Patent Application Publication No. 2012-022028, a sheet-shaped member (quantum-dot sheet) that contains quantum dots is used as a conversion member.
Moreover, local dimming control is proposed as a technique related to a backlight apparatus. In local dimming control, the emission brightness of a plurality of light sources (LEDs) provided in a plurality of divided regions that constitutes a screen region is controlled individually, whereby the emission brightness of a backlight apparatus is changed partially. For example, in the local dimming control, for each of the plurality of divided regions, a brightness value of image data to be displayed in the divided region is analyzed, and the emission brightness of a light source provided in the divided region is controlled based on an analysis result of brightness values. By performing local dimming control, it is possible to increase the contrast of a display image (the image displayed on the screen).
However, in the light source apparatus having the conversion member, light is emitted from a phosphor in various directions. Due to this, light emitted from the phosphor in a certain divided region leaks to another divided region, and a brightness unevenness or a color unevenness occurs in the light emitted from the light source apparatus. Such a brightness unevenness or such a color unevenness appears more remarkable when local dimming control is executed. Moreover, it is difficult to suppress such a brightness unevenness or such a color unevenness even when the conventional technique is applied.